This application relates to lasers and laser stabilization.
A laser can be subject to various perturbations and changes and the laser operations can be adversely affected by such perturbations and changes. For example, temperature fluctuations and vibrations can cause the laser to fluctuate in the laser wavelength, and the laser power level and the optical phase of the laser. Various laser stabilization techniques can be used to stabilize a laser against perturbations and changes and to reduce the laser linewidth.
One example of laser stabilization techniques uses a Fabry-Perot cavity as an optical reference to detect a change in the laser frequency with respect to a resonance frequency of the Fabry-Perot cavity and an error signal is generated based on this frequency change and is fed into an electronic locking circuit that tunes the laser to lock or stabilize the laser frequency relative to the resonance frequency of the Fabry-Perot cavity. In addition to the above electronic feedback and locking, a Fabry-Perot cavity can be used as an optical frequency reference to directly provide optical feedback to a laser in an optical injection locking scheme to stabilize the laser. For example, the laser output of a semiconductor laser can be directed into an external reference Fabry-Perot cavity and the optical reflection or transmission of the external Fabry-Perot cavity can be directed back into the semiconductor laser to stabilize the laser wavelength and to reduce the laser linewidth of the semiconductor laser.